Why Netflix can’t keep winning

FORTUNE — It’s only logical that Netflix will lose its dominance over the video-streaming business. It’s been slowly happening for a couple of years. Competitors have been piling in. Netflix is losing some big providers of movies and TV and paying more to the ones it lands or retains. That situation is likely to continue as more licenses come up for renewal.

It’s not a question of if Netflix NFLX will lose its dominance, but when. And yet, the debate about the company’s fate rages on, and the stock price is rising rather than falling. It’s up more than 10% just since the beginning of the year, to just about $100—which is better than the $295 it was getting in July of 2011 but still inflated. Investors act “as if it’s the undisputed leader,” CNNMoney’s Paul LaMonica remarked earlier this month. And it is, but not for long.

The stock price seems it has little to do with Netflix’s long-term or even medium-term prospects. Witness the note issued last week by Jon C. Ogg of Janney Capital. He raised his rating from “neutral” to “buy,” with a price target of $129, based largely on this conclusion: “Competition has not yet materialized to the extent that it poses significant near-term risk.” Once past the “near term,” however, things look a little different. HBO recently struck a deal with Universal Pictures that will make it—and its streaming service HBO Go—the exclusive outlet for those movies for the next 10 years. HBO also has similar deals with other studios including Fox NWS and Warner Bros TWX.

Netflix will never have those movies. And there are rumblings that HBO might decide to make its Go service available to consumers who don’t have cable. If that happens, the whole market will go topsy-turvy, and Netflix will be that much less necessary for a lot of people. After all, HBO not only has access to the film libraries of other companies it is already making high-quality, highly desirable original content Netflix, Hulu and Amazon are struggling to create. If, as many observers expect, Netflix snags movies from Sony SNE, that will be a big coup for the company depending on the deal’s terms.

Much has been made of the deal Netflix struck with Disney DIS and Netflix’s ability to stream Disney classics like Alice in Wonderland will no doubt help its cause. But it won’t be able to stream new Disney movies until 2016. That includes the wildly popular Pixar titles. Meanwhile, other streamers are making strides in television programming. One big Netflix competitor, Hulu, is in turmoil just now with the sudden departure of CEO Jason Kilar. Nobody knows what might happen with that service, owned by several TV networks.

Amazon recently inked a deal with A&E, which will give it access to programming from the A&E channel, the History Channel, and Lifetime. (Amazon also reached a deal with Epix, giving it access to movies from Paramount, MGM, and Lionsgate. Netflix has the same deal but anything that boosts a competitor’s offerings is going to help draw customers away.)

Hulu for now is still tops for TV programming, with far more new (or relatively new) TV shows than either Amazon or Netflix. But that could change in an instant, especially given Hulu’s TV-network owners ambivalence about the service. Kilar had worked feverishly to keep those networks on board, and now he’s leaving. They might well decide to spread the programming around, and almost certainly not exclusively to Netflix.

Meanwhile, there is a lot more competition coming, as Redbox owner Coinstar CSTR and telecom giant Verizon roll out their new streaming service. And whatever Apple has coming is making everyone nervous—almost certainly Hastings most of all. Obviously, none of this means that Netflix won’t go on to thrive —it’s just that in order to do so, it will have to behave as it never had to before: like a competitor in a cutthroat market, both in licensing and customer acquisition and retention.